#include "backup_system.h"
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <dirent.h>
#include <fcntl.h>
#include <errno.h>

// Utility function to get current time in microseconds
static uint64_t get_time_microseconds(void) {
    struct timeval tv;
    gettimeofday(&tv, NULL);
    return (uint64_t)tv.tv_sec * 1000000 + tv.tv_usec;
}

// Convert backup type to string
const char* backup_type_to_string(backup_type_t type) {
    switch (type) {
        case BACKUP_TYPE_FULL: return "FULL";
        case BACKUP_TYPE_INCREMENTAL: return "INCREMENTAL";
        case BACKUP_TYPE_DIFFERENTIAL: return "DIFFERENTIAL";
        case BACKUP_TYPE_LOG: return "LOG";
        default: return "UNKNOWN";
    }
}

// Convert backup status to string
const char* backup_status_to_string(backup_status_t status) {
    switch (status) {
        case BACKUP_STATUS_PENDING: return "PENDING";
        case BACKUP_STATUS_RUNNING: return "RUNNING";
        case BACKUP_STATUS_COMPLETED: return "COMPLETED";
        case BACKUP_STATUS_FAILED: return "FAILED";
        case BACKUP_STATUS_CANCELLED: return "CANCELLED";
        default: return "UNKNOWN";
    }
}

// Convert recovery type to string
const char* recovery_type_to_string(recovery_type_t type) {
    switch (type) {
        case RECOVERY_TYPE_FULL: return "FULL";
        case RECOVERY_TYPE_POINT_IN_TIME: return "POINT_IN_TIME";
        case RECOVERY_TYPE_TRANSACTION: return "TRANSACTION";
        case RECOVERY_TYPE_PAGE: return "PAGE";
        default: return "UNKNOWN";
    }
}

// Calculate file checksum (simplified CRC64)
uint64_t calculate_file_checksum(const char* filename) {
    if (!filename) return 0;
    
    FILE* file = fopen(filename, "rb");
    if (!file) return 0;
    
    uint64_t checksum = 0;
    uint8_t buffer[8192];
    size_t bytes_read;
    
    while ((bytes_read = fread(buffer, 1, sizeof(buffer), file)) > 0) {
        for (size_t i = 0; i < bytes_read; i++) {
            checksum = checksum * 31 + buffer[i];
        }
    }
    
    fclose(file);
    return checksum;
}

// Create backup system
backup_system_t* backup_system_create(const backup_config_t* config, gudb* database) {
    if (!config || !database) {
        return NULL;
    }
    
    backup_system_t* system = calloc(1, sizeof(backup_system_t));
    if (!system) {
        return NULL;
    }
    
    // Copy configuration
    memcpy(&system->config, config, sizeof(backup_config_t));
    system->database = database;
    
    // Initialize limits
    system->max_manifests = 1000;
    system->manifests = calloc(system->max_manifests, sizeof(backup_manifest_t*));
    if (!system->manifests) {
        free(system);
        return NULL;
    }
    
    // Initialize synchronization primitives
    if (pthread_rwlock_init(&system->manifests_lock, NULL) != 0 ||
        pthread_mutex_init(&system->jobs_mutex, NULL) != 0 ||
        pthread_mutex_init(&system->stats_mutex, NULL) != 0 ||
        pthread_cond_init(&system->job_cond, NULL) != 0) {
        free(system->manifests);
        free(system);
        return NULL;
    }
    
    system->start_time = time(NULL);
    system->next_backup_id = 1;
    system->next_job_id = 1;
    system->next_recovery_id = 1;
    system->initialized = false;
    system->shutting_down = false;
    system->threads_running = false;
    
    return system;
}

// Initialize backup system
int backup_system_init(backup_system_t* system, logger_t* logger) {
    if (!system || system->initialized) {
        return -1;
    }
    
    system->logger = logger;
    
    // Create backup directory if it doesn't exist
    struct stat st;
    if (stat(system->config.backup_directory, &st) != 0) {
        if (mkdir(system->config.backup_directory, 0755) != 0) {
            LOG_ERROR("BACKUP_SYSTEM", "Failed to create backup directory: %s", 
                     system->config.backup_directory);
            return -1;
        }
    }
    
    system->initialized = true;
    
    LOG_INFO("BACKUP_SYSTEM", 
             "Backup system initialized: directory=%s, max_threads=%u, retention=%u days",
             system->config.backup_directory,
             system->config.max_backup_threads,
             system->config.retention_days);
    
    return 0;
}

// Destroy backup system
void backup_system_destroy(backup_system_t* system) {
    if (!system) {
        return;
    }
    
    LOG_INFO("BACKUP_SYSTEM", "Shutting down backup system");
    
    // Signal shutdown
    system->shutting_down = true;
    
    // Stop background threads
    backup_system_stop_threads(system);
    
    // Clean up manifests
    pthread_rwlock_wrlock(&system->manifests_lock);
    for (uint32_t i = 0; i < system->manifest_count; i++) {
        backup_manifest_t* manifest = system->manifests[i];
        if (manifest) {
            free(manifest->files);
            free(manifest->dependency_ids);
            free(manifest);
        }
    }
    pthread_rwlock_unlock(&system->manifests_lock);
    
    // Clean up jobs
    pthread_mutex_lock(&system->jobs_mutex);
    backup_job_t* job = system->active_jobs;
    while (job) {
        backup_job_t* next = job->next;
        if (job->thread_active) {
            pthread_cancel(job->thread);
            pthread_join(job->thread, NULL);
        }
        pthread_mutex_destroy(&job->mutex);
        free(job);
        job = next;
    }
    
    job = system->completed_jobs;
    while (job) {
        backup_job_t* next = job->next;
        pthread_mutex_destroy(&job->mutex);
        free(job);
        job = next;
    }
    pthread_mutex_unlock(&system->jobs_mutex);
    
    // Clean up recovery contexts
    recovery_context_t* recovery = system->active_recoveries;
    while (recovery) {
        recovery_context_t* next = (recovery_context_t*)recovery; // Simplified
        free(recovery);
        recovery = next;
    }
    
    // Clean up synchronization primitives
    pthread_rwlock_destroy(&system->manifests_lock);
    pthread_mutex_destroy(&system->jobs_mutex);
    pthread_mutex_destroy(&system->stats_mutex);
    pthread_cond_destroy(&system->job_cond);
    
    // Free memory
    free(system->manifests);
    free(system);
    
    LOG_INFO("BACKUP_SYSTEM", "Backup system destroyed");
}

// Start background threads
int backup_system_start_threads(backup_system_t* system) {
    if (!system || system->threads_running) {
        return -1;
    }
    
    system->threads_running = true;
    
    // Start scheduler thread
    if (pthread_create(&system->scheduler_thread, NULL, 
                      backup_system_scheduler_thread, system) != 0) {
        system->threads_running = false;
        return -1;
    }
    
    // Start cleanup thread
    if (pthread_create(&system->cleanup_thread, NULL, 
                      backup_system_cleanup_thread, system) != 0) {
        system->threads_running = false;
        pthread_cancel(system->scheduler_thread);
        return -1;
    }
    
    LOG_INFO("BACKUP_SYSTEM", "Background threads started");
    return 0;
}

// Stop background threads
int backup_system_stop_threads(backup_system_t* system) {
    if (!system || !system->threads_running) {
        return -1;
    }
    
    system->threads_running = false;
    
    // Signal and join threads
    pthread_cond_broadcast(&system->job_cond);
    
    pthread_cancel(system->scheduler_thread);
    pthread_cancel(system->cleanup_thread);
    
    pthread_join(system->scheduler_thread, NULL);
    pthread_join(system->cleanup_thread, NULL);
    
    LOG_INFO("BACKUP_SYSTEM", "Background threads stopped");
    return 0;
}

// Create backup job
uint64_t backup_system_create_backup(backup_system_t* system,
                                     backup_type_t type,
                                     const char* description) {
    if (!system || !system->initialized) {
        return 0;
    }
    
    pthread_mutex_lock(&system->jobs_mutex);
    
    // Create backup job
    backup_job_t* job = calloc(1, sizeof(backup_job_t));
    if (!job) {
        pthread_mutex_unlock(&system->jobs_mutex);
        return 0;
    }
    
    // Initialize job
    job->job_id = system->next_job_id++;
    job->backup_type = type;
    job->status = BACKUP_STATUS_PENDING;
    job->start_time = time(NULL);
    job->progress_percent = 0.0;
    job->can_cancel = true;
    
    // Set backup path
    snprintf(job->backup_path, sizeof(job->backup_path),
             "%s/backup_%llu_%s_%ld",
             system->config.backup_directory,
             job->job_id,
             backup_type_to_string(type),
             job->start_time);
    
    // Initialize job mutex
    if (pthread_mutex_init(&job->mutex, NULL) != 0) {
        free(job);
        pthread_mutex_unlock(&system->jobs_mutex);
        return 0;
    }
    
    // Add to active jobs list
    job->next = system->active_jobs;
    if (system->active_jobs) {
        system->active_jobs->prev = job;
    }
    system->active_jobs = job;
    system->active_job_count++;
    
    uint64_t job_id = job->job_id;
    
    pthread_mutex_unlock(&system->jobs_mutex);
    
    // Start backup thread
    if (pthread_create(&job->thread, NULL, backup_job_thread, job) == 0) {
        job->thread_active = true;
        LOG_INFO("BACKUP_SYSTEM", 
                 "Created %s backup job %llu: %s",
                 backup_type_to_string(type), job_id,
                 description ? description : "");
    } else {
        job->status = BACKUP_STATUS_FAILED;
        strcpy(job->error_message, "Failed to create backup thread");
        LOG_ERROR("BACKUP_SYSTEM", "Failed to create backup thread for job %llu", job_id);
    }
    
    // Signal job condition
    pthread_cond_signal(&system->job_cond);
    
    return job_id;
}

// Get backup job
backup_job_t* backup_system_get_job(backup_system_t* system, uint64_t job_id) {
    if (!system) {
        return NULL;
    }
    
    pthread_mutex_lock(&system->jobs_mutex);
    
    // Search active jobs
    backup_job_t* job = system->active_jobs;
    while (job) {
        if (job->job_id == job_id) {
            pthread_mutex_unlock(&system->jobs_mutex);
            return job;
        }
        job = job->next;
    }
    
    // Search completed jobs
    job = system->completed_jobs;
    while (job) {
        if (job->job_id == job_id) {
            pthread_mutex_unlock(&system->jobs_mutex);
            return job;
        }
        job = job->next;
    }
    
    pthread_mutex_unlock(&system->jobs_mutex);
    return NULL;
}

// Create backup manifest
backup_manifest_t* backup_system_create_manifest(backup_system_t* system,
                                                 backup_type_t type,
                                                 const char* description) {
    if (!system) {
        return NULL;
    }
    
    backup_manifest_t* manifest = calloc(1, sizeof(backup_manifest_t));
    if (!manifest) {
        return NULL;
    }
    
    // Initialize manifest
    manifest->backup_id = system->next_backup_id++;
    manifest->backup_type = type;
    manifest->backup_start_time = time(NULL);
    manifest->database_size = 0; // Would be calculated from actual database
    strcpy(manifest->database_version, "1.0.0");
    strcpy(manifest->backup_version, "1.0.0");
    manifest->is_valid = true;
    manifest->is_archived = false;
    
    if (description) {
        strncpy(manifest->description, description, sizeof(manifest->description) - 1);
    }
    
    // Get hostname and username
    gethostname(manifest->hostname, sizeof(manifest->hostname) - 1);
    strcpy(manifest->created_by, "backup_system");
    
    return manifest;
}

// Save backup manifest
int backup_system_save_manifest(backup_system_t* system, backup_manifest_t* manifest) {
    if (!system || !manifest) {
        return -1;
    }
    
    pthread_rwlock_wrlock(&system->manifests_lock);
    
    // Find empty slot or expand array
    uint32_t slot = system->manifest_count;
    if (slot >= system->max_manifests) {
        pthread_rwlock_unlock(&system->manifests_lock);
        return -1; // Array full
    }
    
    // Save manifest
    system->manifests[slot] = manifest;
    system->manifest_count++;
    
    pthread_rwlock_unlock(&system->manifests_lock);
    
    // Write manifest to file
    char manifest_path[1024];
    snprintf(manifest_path, sizeof(manifest_path),
             "%s/manifest_%llu.json",
             system->config.backup_directory,
             manifest->backup_id);
    
    FILE* file = fopen(manifest_path, "w");
    if (file) {
        fprintf(file, "{\n");
        fprintf(file, "  \"backup_id\": %llu,\n", manifest->backup_id);
        fprintf(file, "  \"backup_type\": \"%s\",\n", backup_type_to_string(manifest->backup_type));
        fprintf(file, "  \"start_time\": %ld,\n", manifest->backup_start_time);
        fprintf(file, "  \"end_time\": %ld,\n", manifest->backup_end_time);
        fprintf(file, "  \"database_size\": %llu,\n", manifest->database_size);
        fprintf(file, "  \"backup_size\": %llu,\n", manifest->backup_size);
        fprintf(file, "  \"file_count\": %u,\n", manifest->file_count);
        fprintf(file, "  \"description\": \"%s\",\n", manifest->description);
        fprintf(file, "  \"created_by\": \"%s\",\n", manifest->created_by);
        fprintf(file, "  \"hostname\": \"%s\",\n", manifest->hostname);
        fprintf(file, "  \"is_valid\": %s\n", manifest->is_valid ? "true" : "false");
        fprintf(file, "}\n");
        fclose(file);
        
        LOG_INFO("BACKUP_SYSTEM", "Saved manifest for backup %llu", manifest->backup_id);
        return 0;
    }
    
    return -1;
}

// List backups
int backup_system_list_backups(backup_system_t* system,
                               backup_manifest_t*** manifests,
                               uint32_t* count) {
    if (!system || !manifests || !count) {
        return -1;
    }
    
    pthread_rwlock_rdlock(&system->manifests_lock);
    
    *count = system->manifest_count;
    if (*count == 0) {
        *manifests = NULL;
        pthread_rwlock_unlock(&system->manifests_lock);
        return 0;
    }
    
    // Allocate array for manifest pointers
    *manifests = malloc(sizeof(backup_manifest_t*) * (*count));
    if (!*manifests) {
        pthread_rwlock_unlock(&system->manifests_lock);
        return -1;
    }
    
    // Copy manifest pointers
    for (uint32_t i = 0; i < *count; i++) {
        (*manifests)[i] = system->manifests[i];
    }
    
    pthread_rwlock_unlock(&system->manifests_lock);
    return 0;
}

// Verify backup integrity
int backup_system_verify_backup(backup_system_t* system, uint64_t backup_id) {
    if (!system) {
        return -1;
    }
    
    // Find manifest
    pthread_rwlock_rdlock(&system->manifests_lock);
    backup_manifest_t* manifest = NULL;
    for (uint32_t i = 0; i < system->manifest_count; i++) {
        if (system->manifests[i] && system->manifests[i]->backup_id == backup_id) {
            manifest = system->manifests[i];
            break;
        }
    }
    pthread_rwlock_unlock(&system->manifests_lock);
    
    if (!manifest) {
        LOG_ERROR("BACKUP_SYSTEM", "Backup %llu not found", backup_id);
        return -1;
    }
    
    // Verify each file in backup
    int errors = 0;
    for (uint32_t i = 0; i < manifest->file_count; i++) {
        backup_file_info_t* file_info = &manifest->files[i];
        
        // Check if file exists
        if (access(file_info->full_path, F_OK) != 0) {
            LOG_ERROR("BACKUP_SYSTEM", "Backup file missing: %s", file_info->full_path);
            errors++;
            continue;
        }
        
        // Verify checksum
        uint64_t actual_checksum = calculate_file_checksum(file_info->full_path);
        if (actual_checksum != file_info->checksum) {
            LOG_ERROR("BACKUP_SYSTEM", "Checksum mismatch for file: %s", file_info->full_path);
            errors++;
        }
    }
    
    if (errors == 0) {
        LOG_INFO("BACKUP_SYSTEM", "Backup %llu verification successful", backup_id);
        return 0;
    } else {
        LOG_ERROR("BACKUP_SYSTEM", "Backup %llu verification failed with %d errors", 
                 backup_id, errors);
        return -1;
    }
}

// Get system statistics
int backup_system_get_stats(backup_system_t* system, backup_system_stats_t* stats) {
    if (!system || !stats) {
        return -1;
    }
    
    pthread_mutex_lock(&system->stats_mutex);
    memcpy(stats, &system->stats, sizeof(backup_system_stats_t));
    pthread_mutex_unlock(&system->stats_mutex);
    
    return 0;
}

// Print system statistics
void backup_system_print_stats(backup_system_t* system) {
    if (!system) {
        return;
    }
    
    backup_system_stats_t stats;
    if (backup_system_get_stats(system, &stats) != 0) {
        return;
    }
    
    LOG_INFO("BACKUP_STATS", 
             "Total Backups: %llu, Successful: %llu, Failed: %llu, "
             "Total Size: %llu bytes, Compressed: %llu bytes, "
             "Compression Ratio: %.2f%%, Active Jobs: %u",
             stats.total_backups,
             stats.successful_backups,
             stats.failed_backups,
             stats.total_backup_size,
             stats.compressed_size,
             stats.compression_ratio * 100.0,
             stats.active_jobs);
}

// Backup job thread function
void* backup_job_thread(void* arg) {
    backup_job_t* job = (backup_job_t*)arg;
    if (!job) {
        return NULL;
    }
    
    LOG_INFO("BACKUP_SYSTEM", "Starting backup job %llu", job->job_id);
    
    pthread_mutex_lock(&job->mutex);
    job->status = BACKUP_STATUS_RUNNING;
    job->start_time = time(NULL);
    pthread_mutex_unlock(&job->mutex);
    
    // Simulate backup work
    for (int i = 0; i < 100 && !job->cancelled; i++) {
        usleep(50000); // 50ms sleep to simulate work
        
        pthread_mutex_lock(&job->mutex);
        job->progress_percent = (double)i;
        job->bytes_processed = i * 1024; // Simulate progress
        pthread_mutex_unlock(&job->mutex);
    }
    
    pthread_mutex_lock(&job->mutex);
    if (job->cancelled) {
        job->status = BACKUP_STATUS_CANCELLED;
        LOG_INFO("BACKUP_SYSTEM", "Backup job %llu cancelled", job->job_id);
    } else {
        job->status = BACKUP_STATUS_COMPLETED;
        job->progress_percent = 100.0;
        job->end_time = time(NULL);
        LOG_INFO("BACKUP_SYSTEM", "Backup job %llu completed successfully", job->job_id);
    }
    pthread_mutex_unlock(&job->mutex);
    
    return NULL;
}

// Scheduler thread function
void* backup_system_scheduler_thread(void* arg) {
    backup_system_t* system = (backup_system_t*)arg;
    if (!system) {
        return NULL;
    }
    
    LOG_DEBUG("BACKUP_SYSTEM", "Scheduler thread started");
    
    while (system->threads_running && !system->shutting_down) {
        sleep(60); // Check every minute
        
        if (!system->threads_running || system->shutting_down) {
            break;
        }
        
        // Update statistics
        backup_system_update_stats(system);
        
        // Cleanup completed jobs (keep last 10)
        pthread_mutex_lock(&system->jobs_mutex);
        backup_job_t* job = system->completed_jobs;
        int count = 0;
        while (job) {
            count++;
            if (count > 10) {
                backup_job_t* next = job->next;
                if (job->prev) {
                    job->prev->next = job->next;
                }
                if (job->next) {
                    job->next->prev = job->prev;
                }
                pthread_mutex_destroy(&job->mutex);
                free(job);
                job = next;
            } else {
                job = job->next;
            }
        }
        pthread_mutex_unlock(&system->jobs_mutex);
    }
    
    LOG_DEBUG("BACKUP_SYSTEM", "Scheduler thread stopped");
    return NULL;
}

// Cleanup thread function
void* backup_system_cleanup_thread(void* arg) {
    backup_system_t* system = (backup_system_t*)arg;
    if (!system) {
        return NULL;
    }
    
    LOG_DEBUG("BACKUP_SYSTEM", "Cleanup thread started");
    
    while (system->threads_running && !system->shutting_down) {
        sleep(3600); // Check every hour
        
        if (!system->threads_running || system->shutting_down) {
            break;
        }
        
        // Cleanup old backups based on retention policy
        backup_system_cleanup_old_backups(system);
    }
    
    LOG_DEBUG("BACKUP_SYSTEM", "Cleanup thread stopped");
    return NULL;
}

// Update system statistics
int backup_system_update_stats(backup_system_t* system) {
    if (!system) {
        return -1;
    }
    
    pthread_mutex_lock(&system->stats_mutex);
    pthread_mutex_lock(&system->jobs_mutex);
    
    // Count active jobs
    system->stats.active_jobs = system->active_job_count;
    
    pthread_mutex_unlock(&system->jobs_mutex);
    pthread_mutex_unlock(&system->stats_mutex);
    
    return 0;
}

// Cleanup old backups
int backup_system_cleanup_old_backups(backup_system_t* system) {
    if (!system) {
        return -1;
    }
    
    time_t cutoff_time = time(NULL) - (system->config.retention_days * 24 * 3600);
    int cleaned_count = 0;
    
    pthread_rwlock_wrlock(&system->manifests_lock);
    
    for (uint32_t i = 0; i < system->manifest_count; i++) {
        backup_manifest_t* manifest = system->manifests[i];
        if (manifest && manifest->backup_start_time < cutoff_time) {
            LOG_INFO("BACKUP_SYSTEM", "Cleaning up old backup %llu", manifest->backup_id);
            
            // Remove manifest file
            char manifest_path[1024];
            snprintf(manifest_path, sizeof(manifest_path),
                     "%s/manifest_%llu.json",
                     system->config.backup_directory,
                     manifest->backup_id);
            unlink(manifest_path);
            
            // Free manifest
            free(manifest->files);
            free(manifest->dependency_ids);
            free(manifest);
            system->manifests[i] = NULL;
            cleaned_count++;
        }
    }
    
    // Compact array
    uint32_t write_pos = 0;
    for (uint32_t read_pos = 0; read_pos < system->manifest_count; read_pos++) {
        if (system->manifests[read_pos]) {
            system->manifests[write_pos++] = system->manifests[read_pos];
        }
    }
    system->manifest_count = write_pos;
    
    pthread_rwlock_unlock(&system->manifests_lock);
    
    if (cleaned_count > 0) {
        LOG_INFO("BACKUP_SYSTEM", "Cleaned up %d old backups", cleaned_count);
    }
    
    return cleaned_count;
}

// Simplified compression function (would use real compression libraries)
int compress_file(const char* input_file, const char* output_file, 
                 compression_type_t compression) {
    if (!input_file || !output_file) {
        return -1;
    }
    
    // This is a placeholder - real implementation would use gzip, lz4, etc.
    FILE* in = fopen(input_file, "rb");
    if (!in) return -1;
    
    FILE* out = fopen(output_file, "wb");
    if (!out) {
        fclose(in);
        return -1;
    }
    
    // Simple copy for now (placeholder for real compression)
    char buffer[8192];
    size_t bytes;
    while ((bytes = fread(buffer, 1, sizeof(buffer), in)) > 0) {
        fwrite(buffer, 1, bytes, out);
    }
    
    fclose(in);
    fclose(out);
    
    return 0;
}

// Simplified decompression function
int decompress_file(const char* input_file, const char* output_file,
                   compression_type_t compression) {
    // Placeholder - would implement real decompression
    return compress_file(input_file, output_file, compression);
}